CST3 and chronic kidney disease: Most studies used creatinine based algorithms, and the majority the Modification of Diet in Renal Disease 4-variable (MDRD-4) equation, except Zoccali et al. [55] who used the Chronic Kidney Disease Epidemiology Collaboration (CKD–EPI) Creatinine-Cystatin C algorithm, that incorporates both creatinine and cystatin C. Plasma creatinine is significantly affected by age, nutrition, gender, physical activity and muscle mass [65, 66].